A fourteen–year study of finches on the Galapagos islands concluded that there is a definite relationship between cli...

Victoria on June 27, 2020

Hi @yckim2180,

Happy to help!

We are looking for the answer choice which outlines the assumption that is necessary for the passage to properly draw its conclusion. The correct answer choice will be the one that, when negated, no longer allows the conclusion to be drawn.

The passage tells us that a study of finches on the Galápagos Islands concluded that there is a definite relationship between climate and the population size of finch species which thrive there.

Drought - more members of larger species survive because their bills are big enough to crack large, hard seeds; smaller birds are not able to eat these seeds

Rain - fewer member of larger species survive because the rain supports the growth of plants which produce small seeds; some larger finches cannot keep up because they must consume so many small seeds to meet their energy demands

Answer choice (B) is correct because the negation of this assumption no longer allows the conclusion to be properly drawn. If rain does not necessarily result in fewer large, hard seeds being produced, then it doesn't make sense that the decrease in larger finches is due to the rain as they would still be able to eat the same amount of large, hard seeds.

The assumption allows the conclusion to be properly drawn as a decrease in the number of large, hard seeds would mean that the finches would be forced to eat the smaller seeds, resulting in the decrease in larger finches as outlined in the passage.

Hope this is helpful! Please let us know if you have any further questions.

YAS1 on September 23, 2020

^ based on the explanation above, would this question be considered strengthen with necessary premise?

MarsfromFl on October 7, 2020

^Right, I think that is what confused me. I was looking for sufficient, not necessary.

Emil-Kunkin on August 27 at 02:31AM

I would call this a necessary assumption question. It asks what must be assumed for the argument to be justified. While it is likely the answer will also be a sufficient assumption, it must be one that is necessary, that is, something that if were not true would kill the argument. The key element here for me is that we are looking for the thing that MUST be assumed. there are often multiple sufficient assumptions, so none of them truly must be assumed.

I would note that this is a more common way they asked question in the past, and more modern tests will usually not have such a convoluted stem. That said, if one were to get a question like this on the test, you should try to just answer what the stem asks for. That is, something that is necessary to justify the conclusion- something that must be true for the conclusion to be justified.